Data Gathering

Introduction:

Before studying the impacts of frac sand mining on western Wisconsin, several data sets are needed. The goal of this lab was to build familiarity with data acquisition from a plethora of sources. It also served to prepare the data for future geoprocessing operations.

Methods:

Data were sourced from several organizations:

• Land Cover and Elevation data were acquired from the U.S. Geologic Survey via The National Map viewer.
• Rail Lines data were acquired from the U.S. Department of Transportation via the National Transportation Atlas Database 2015.
• Cropland data for Wisconsin were acquired from the U.S. Department of Agriculture via the Natural Resources Conservation Service Geospatial Data Gateway.
• Soil data were acquired from the U.S. Department of Agriculture via the Web Soil Survey App.
• All other data for Trempealeau County, Wisconsin were acquired from the county Land Records Office.

Figure 1: Maps of Trempealeau County
made with data sourced from several agencies.

Data Accuracy:

The data were judged on the following criteria:

• Scale - What scale the data were designed to be used.
• Effective Resolution - The ideal pixel size for a specific scale.
• Minimum Mapping Unit - The smallest depictable or plottable object at a certain scale.
• Planimetric Coordinate Accuracy - How close the points are to their real locations on Earth.
• Lineage - Documentation recording how the data were collected and processed, and by whom.
• Temporal Accuracy - How up to date the data are. When the data were published.
• Attribute Accuracy - How accurate the data classifications were when compared to the real world. Recorded as a specific number for metric attributes, and as a accuracy percentage for categorical attributes.

Figure 2: The Accuracy Assessment.

Conclusions:

This exercise will affect how I use certain data sets in future exercises in this class. I will preferentially use the USDA crop data over the USGS land cover data whenever I can, as the USDA validated the accuracy of their data. If I am to use the railroads data to perform any sort of analysis, I should download an updated version of the data, as it is updated incredibly frequently. I should be aware that the USGS land cover data is due for an update next year, and isn't necessarily going to show recent development.